please solve this within 35 minutes

b) It is believed that sufferers of a cold virus experience symptoms for seven days. However, the total number of days is a normally distributed random variable whose mean is 7.5 days and the standard deviation is 1.2 days. i. What is the probability of a cold sufferer experiencing symptoms for at least FOUR (4} days? (4 marks) ii. What is the probability of a cold sufferer experiencing symptoms between SEVEN (7} and TEN (10) days? (5 marks} iii. What is the minimum number of days in which 67% of cold sufferers experience symptoms? (4 marks)